This invention relates generally to method and apparatus for teaching robot station locations, and in accordance with one embodiment of the invention to method and apparatus for teaching robot station locations for application to a chemical mechanical planarization method and apparatus.
Robots are used in many and varied manufacturing applications. One attribute of a mechanical robot that makes the robot useful in such applications is the ability of the robot to carry out a repetitive operation with great precision. For example, a robot is able to repetitively and precisely move objects, held by the arm of the robot, from point A to point B. In order to carry out such movements successfully, however, the robot must first be calibrated, or xe2x80x9ctaughtxe2x80x9d the location and orientation of the points A and B.
The process of teaching a robot station location is often done visually by a human operator. The operator controls the robot arm manually to position the end of the arm or a work piece carried by the arm in what is visually perceived to be the correct position. Once so located or positioned, the coordinates and orientation of the robot arm are recorded so that the robot can always return the arm or the work piece to that location and orientation. This method of robot station location, however, is fraught with difficulties. The accuracy of the positioning is subject to the skill and visual acuity of the operator. In addition, in many instances the final desired position is not clearly observable by the operator. For example, in robotically positioning a work piece such as a semiconductor wafer with respect to some chemical mechanical planarization (CMP) equipment, the correct position is at least partially obscured and is not readily observable.
Accordingly, a need exists for a method and apparatus that will allow the teaching of robot station location without reliance on operator visual perception.